Wood-Based Cellulose-Rich Ultrafiltration Membranes: Alkaline Coagulation Bath Introduction and Investigation of Its Effect over Membranes' Performance.

In this study, wood-based cellulose-rich membranes were produced with a novel approach to casting procedure. Flat-sheet membranes were prepared from birch biomass pretreated with deep eutectic solvent and dissolved in ionic liquid-dimethylsulfoxide system via phase inversion method. Alkaline coagulation bath filled with sodium hydroxide solution was added to the process before a water coagulation bath and aimed to improve membranes' performance. The effect of NaOH coagulation bath on the membrane was studied based on two NaOH concentrations and two different treatment times. The characterisation methods included measuring pure water permeabilities, polyethylene glycol 35 kDa model solution retentions, hydrophilicity, zeta potential, and chemical structure. Additionally, suitability of the membranes for removing residual phosphorous from a municipal wastewater treatment plant's effluent was studied. The study revealed that introduction of the alkaline coagulation bath led to additional removal of lignin from membrane matrix and increase in the filtration capacity up to eight times. The resulting membranes can be characterised as very hydrophilic, with contact angle values 11.9-18.2°, negatively charged over a wide pH range. The membranes with the highest permeability, 380-450 L/m2·h·bar, showed approximately 70% phosphorus removal from purified wastewater, good removal of suspended solids, and low irreversible fouling tendency.

A synergic approach for nutrient recovery and biodiesel production by the cultivation of microalga species in the fertilizer plant wastewater.

The combination of wastewater treatment and biodiesel production using algal cultivation was studied in the present work. The two main goals of the work were achieved by the cultivation of freshwater microalgae such as Chlamydomonas sp., Scenedesmus ecornis, and Scenedesmus communis in two different dilutions of fertilizer plant wastewater (FWWD1 and FWWD2) collected from Yara Suomi Oy, Finland. The growth pattern of different algal species in FWWD1 and FWWD2 was observed. The effect of pH on biomass concentration, lipid content, biomass productivity, and lipid productivity by all three algal species in FWWD1 and FWWD2 were monitored. The maximum biomass concentration and productivity were observed in FWWD1 at pH7.5 for Chlamydomonas sp. and at pH 8.5 for S. ecornis and S. communis. The maximum lipid content was detected in Chlamydomonas sp at pH5.5, followed by S. ecornis and then S. communis at pH 7.5 in FWWD2 obtained after co-solvent extraction method. The most significant removal percentage of COD by all algal species were observed in FWWD1, whereas the highest removal percentage of TN and TP were detected in FWWD2, respectively. The fatty acid methyl ester (FAME) characterization of each algal species in FWWD1 and FWWD2 at their optimum pH was investigated to determine the quality of obtained biodiesel.

Effect of humic acid on anaerobic digestion of cellulose and xylan in completely stirred tank reactors: inhibitory effect, mitigation of the inhibition and the dynamics of the microbial communities.

Inhibition effect of humic acid (HA) on anaerobic digestion of cellulose and xylan and the mitigation potential of the inhibition were evaluated in controlled fed batch reactors at 30 °C and a hydraulic retention time (HRT) of 20 days. Reactor performances were evaluated by biogas production and metabolite measurements for 220 days. Microbial population dynamics of the reactors were monitored with next-generation 16S rRNA gene sequencing at nine different sampling times. Our results showed that increasing levels of HA inhibited the hydrolysis efficiency of the digestion by 40% and concomitantly reduced the methane yield. Addition of hydrolytic enzymes helped to reverse the negative effects of HA, whereas calcium addition did not reverse HA inhibition. Microbiological analyses showed that the relative abundance of hydrolytic/fermentative bacterial groups such as Clostridiales, Bacteroidales and Anaerolineales was significantly lowered by the presence of HA. HA also affected the archaeal populations. Mostly hydrogenotrophic methanogens were negatively affected by HA. The relative abundance of Methanobacteriaceae, Methanomicrobiales-WCHA208 and Unassigned Thermoplasmata WCHA1-57 were negatively affected by the presence of HA, whereas Methanosaetacea was not affected.